In restrooms in public places, which are used by many different people, for example in hotel lobbies, hospitals, schools, and the like, depleted toilet paper rolls are relatively frequently exchanged for new toilet paper rolls, for example, every morning. This task requires the use of both hands, in complicated manipulation, to remove the paper tube cores C of the toilet paper rolls from the holders, to thereafter dispose of them, thus adding discrete elements of labor. Further, the requirement to use paper tube cores requires separate additional material cost, and requires discrete separate additional operations to set the paper tube onto the toilet paper roll winding shaft, prior to winding the toilet paper stock thereon, both of which increase production cost.
It is evident that labor, work steps and production costs can be reduced if paper tube cores are deleted from toilet paper rolls. Therefore, some proposals to produce coreless toilet paper rolls have been tried as follows:
(1) For example, Japanese unexamined patent publication No.5504/1976 and Japanese unexamined utility model publication No.130292/1991 both disclose methods characterized by the toilet paper being directly wound on a winding shaft without a paper tube core, with the winding shaft having a special construction for releasing the wound toilet paper roll. In particular, the winding shaft has movable leaves capable of opening/closing radially by manipulation of air pressure, such that the toilet paper can be wound on the winding shaft directly, while the leaves are expanded, and the wound toilet paper roll can be removed from the shaft by radially retracting the leaves after winding. In the process of winding the toilet paper on the winding shaft, after that shaft starts to rotate, the winding speed is increased to a given rate where it is then maintained. Then, the winding speed is decreased at the end of the winding period, and the rotation comes to a halt when the roll is completed. During this process, the toilet paper feed speed, produced by the paper feeding-and-processing apparatus, is controlled to produce a toilet paper feed rate which is substantially coordinated with the winding speed of the winding shaft, so as to avoid tearing the toilet paper stock, a material which has relatively low tensile strength. This method, however, has a drawback; because the winding tension of the toilet paper is maintained low, the outer or trailing end of the toilet paper on the roll tends to be loose, thus causing a tendency to unravel during subsequent handling. Further, during use of the winding shaft of that published reference, as shown in FIG. 13 hereof, the toilet paper tends to become caught between the mutually adjacent leaves 10 due to the pressure of the winding shaft, so that axially extending projections p are formed on the inner surface of the center hollow of the toilet paper roll T. In use, the projections p, tend to come into contact with the supporting bar of the toilet paper holder, thus producing an uncomfortable clattering noise as the toilet paper is unwound. In a public restroom, this can cause substantial embarrassment, especially if the user is a young woman. Further, when the paper is rapidly pulled from the roll, the paper may have more of a tendency to tear off, rather than to unwind.
(2) Another method of producing a coreless toilet paper roll is found in Japanese Unexamined Utility Model Publication No.61049/1976. Several layers of toilet paper, at the beginning of winding, are bonded together as a substitute for a paper tube core. However, since those bonded layers cannot be used, not all of the toilet paper on the roll can be used. Therefore, this method produces a product which is relatively uneconomical.
Among the foregoing problems, the inventors have paid special attention to the problems, related to producing tightly wound rolls of toilet paper, as basic problems to be solved. The inventors have energetically researched the reasons why toilet paper is not conventionally tightly wound, and have found the following:
At the beginning of winding a toilet paper roll, water or a water-solution of adhesive agent is sprayed onto the paper on the winding shaft in order to temporally fix the paper to the winding shaft or to temporally fix several paper layers together with each other. In this situation, the paper absorbs water and is elongated in both the longitudinal and lateral directions. The elongation in the longitudinal direction, in particular, is about 10% beyond the original length. Therefore, when the paper feed speed and the winding speed are mutually coordinated, because the end of the toilet paper being wound has elongated, the tension has been relaxed as the winding commences. Therefore, the inner-most portion of the toilet paper roll T tends to be loose after winding.
Further, near the end of the winding period, both the winding shaft and paper feeding-and-processing apparatus are gradually decelerated and come to halt as the winding is completed. During this deceleration, the toilet paper tends to move at a speed which is faster than the mechanical winder shaft, due to the inertia of the moving stream of the toilet paper. Therefore, again because of the reduced tension, the outside portion of the toilet paper roll tends to be loose.
Though the various reasons, as to why conventional toilet paper is not uniformly tightly wound into rolls, have been made clear through the research of the inventors, as mentioned above, it is still understood by those skilled in the art that consumable toilet paper rolls cannot be produced without winding the toilet paper around a paper tube C as a core, since the toilet paper has characteristics of low density, high flexibility due to crepe treatment or the like, and very low strength in comparison with, for example, newsprint or kraft paper for use in producing corrugated cardboard. This understanding, by those skilled in the art, is apparently based on what might be referred to as "technical common sense", in view of the foregoing characteristics of toilet paper. Thus, it seems that, for several decades since the first rolls of toilet paper appeared in the market place, no toilet paper, for use with detachable supporting bars as described above, has been commercially successfully produced and marketed without a paper tube used as a core.
The present invention overcomes the "technical common sense" with a method of producing a coreless toilet paper roll from which the paper will not become unintentionally loose. In other words, the present invention provides a coreless toilet paper roll which does not become loose, which has no inside projections, and from which virtually all of the toilet paper can be used.